Safety anchored multiconductor cable for electric arc furnaces

ABSTRACT

This multiconductor water-cooled electric arc furnace cable has the majority of its conductors secured within the terminal cup by means of solder. In order to prevent the conductors from dropping out of the terminal cup upon a failure of the water-cooling system causing the solder to melt, two of the conductors are additionally bolted to the inner side of the outer wall of each of the terminal cups. This bolted anchorage prevents the cable from leaving the terminal cup and dropping upon melting of the solder and provides the maximum space for the largest possible central tubular cooling water conduit. It consequently prevents serious damage to the furnace or surroundings and possible injury or deaths of workmen resulting from their coming into contact with the high-voltage high-amperage current thus released, since the conductors still remain connected to the transformer.

United States Patent Goodman 1451 Mar. 28, 1972 [54] SAFETY ANCHORED3,456,064 7/1969 Toto ..174/1s c MULTICONDUCTOR CABLE F OR' ELECTRIC ARCFURNACES Primary Examiner-E. A. Goldberg Assistant Examiner-A. T.Grimley [72] Inventor: Daniel J. Goodman, 23236 Westbury n B h 1& B b eAve., St. Clair Shores, Mich. 48080 I 22 Filed: Aug. 13, 1970 [571ABSTRACT [211 App! 63,405 This multiconductor water-cooled electric arcfurnace cable has the ma ority of its conductors secured within theterminal cup by means of solder. ln order to prevent the conductors [52]US. Cl. ..174/l5 C, 174/19, 174/74 R, f dropping out f the terminal cupupon a f il f the 219/130 339/112 water-cooling system causing thesolder to melt, two of the [5 l] Int. Cl. ..H0lb 7/34 conductors areadditionally bolted to the inner side of the [58] new of Search 1 15outer wall of each of the terminal cups. This bolted anchorage 174,47;13/15 339/1 l 12; 219/130 prevents the cable from leaving the terminalcup and dropping upon melting of the solder and provides the maximumspace [5 6] References Cited for the largest possible central tubularcooling water conduit. UNITED STATES PATENTS lt consequently preventsserious damage to the furnace or surroundmgs and possible in ury ordeaths of workmen resulting Grove 5 C from their coming into ontact thehigh-voltage higlpam- 3,055,290 1 l/ 1962 Grove 1 74/15 C perage currentthus released, since the conductors still remain 3, l TOIO t C connectedto the transformer 3,143,593 7/1964 Toto ..l74/15C 3,551,581 12/1970Goodman 174/15 C 7 Claims, 5 Drawing Figures mtm'enme m2 INVENTOR DANIELJ- GOODMAN ATTORNEYS SAFETY ANCHORED MULTICONDUCTOR CABLE FOR ELECTRICARC FURNACES In the drawings, FIG. 1 is a side elevation, partly incentral longitudinal section, of one end of a water-cooled electric arcfurnace cable,

' showing the safety anchorage construction, according to one form ofthe invention;

FIG. 2 is a cross section through the cable rearwardly of the terminal,taken along the line 2-2 in FIG. 1;

FIG. 3 is a fragmentary bottom plan view of one of the cable anchoringdevices, with the conductor-securing solder omitted, looking in thedirection of the line 3-3 in FIG. 1;

FIG. 4 is a fragmentary cross section taken along the line 4-4 in FIG.1, with the solder present; and

FIG. 5 is'a front end elevation of the cable shown in FIG. 1.

Referring to the drawing in detail, FIG. 1 shows a multiconductorwater-cooled electric cable generally designated for electric arcfurnaces, the cable 10 being one of a plurality of such cables extendingbetween a conventional transformer (not shown) and an electric arcfurnace (not shown). At least three such cables are ordinarily employed,one for each phase of thethree-phase current usually used. Due to theheavy current load demand of such furnaces, however, two to four or morecables 10 may be employed for each phase thus often resulting in a totalof six to twelve or more of such cables per furnace. The primary voltageof such a transformer is in the neighborhood of 13,000 volts and thesecondary output 230 to 800 volts, with a secondary circuit at 10,000amperes per phase. Such cables are made in various sizes, one suchsingle cable in a 9,000 MCM size being capable of carrying 21000 amperesand another in an 18,000 MCM size from 45,000 to 50,000 amperes.

In particular, the multiconductor cable 10, of which only the furnaceconnection end unit 12 is shown, consists of a forward terminal 14 andmulticonductor cable unit 15 secured thereto as described below. Theforward terminal 14 is constructed of heavy copper having a forwardconnection portion or blade 16 adapted to be connected to the furnace. Arearward terminal (not shown) of similar construction is connected tothe rearward end of the cable unit 15 and connected to the transformer(not shown). The forward portion 16 has flat opposite sides 18 (FIG. 5)by which it is bolted to the connection with the furnace or transformer,as the case may be. It is also provided with multiple-spaced holes 20extending transversely therethrough. The forward end 22 of the blade 16is provided with a threaded port 24 leading to the forward end of acooling water passageway 26, the opposite end of which is provided witha rearward port 28 opening into the rearward portion or cup 30 of theterminal 14.

The terminal cup 30, as its name suggests, is of hollow cylindricalshape with an outer generally cylindrical surface 32 provided withmultiple annular frustoconical teeth 34 which engage and penetrate theinner surface 36 of a hose 38 of synthetic rubber such as that knowncommercially by the name of neoprene. The forward end of the hose 38 isencircled by multiple longitudinally spaced annular hose clamps 40 whichtightly grip and indent the hose 38 and in a watertight connection, andforce its inner surface 36 into interlocking engagement with the annularteeth 34 on the terminal cup'32.

The tenninal cup 30 is provided adjacent the inner or rearward port 28with a bore 42 opening into a counterbore 44 with an annular shoulder 46extending therebetween. Seated in the bore 42 is the forward end of ariser tube 48, preferably of copper, the rearward end of which is seatedin and snugly engages the inner cylindrical surface 50 of a fluteperforated .core tube 52 of elastic deformable material, such as rubberor synthetic rubber, having multiple spaced perforations 54 therethroughfor the flow of cooling water. The fluted outer surface 56 is engaged bythe perforated tubular jacket 58 of each jacketed conductor 60, theperforations 62 of which lead to the conductor itself, or so-called rope64 of fine copper wire, so-called because of its resemblance to a hempor manila rope.

The perforated forward end of the jacket 58 extends rearwardly for adistance of approximately 2 feet, beyond which its wall becomesimperforate. At this point it is provided with a tubular plastic plug(not shown) held in place by suitable fasteners such as by four brassscrews. The rearward terminal (not shown) as stated above, is similar tothe forward terminal 14 except that the blade thereof corresponding tothe blade 16 is disposed at right angles to the forward blade 16. Theconstruction of the jacketed cable unit 15 and its conductors 60themselves, together with that of the perforated fluted central tube 52,is conventional and its details rearwardly of the section line 2-2 formsno part of the present invention.

The forward end portion 66, of a plurality, preferably two, of theindividual conductors 64, is enclosed in a tubular conductor clamp 68 ashort distance rearwardly of its forward end 70 which abuts the annularshoulder 46. The tubular clamp 68 is of rectangular cross section (FIG.4) and is drilled at 72 to receive the shank of an anchor bolt or stud74 which also passes through a hole 76 in the flattened portion 78 ofthe conductor end portion 66 into a threaded hole 80. Threaded onto theinner end of the bolt or stud 74 is a nut 82. The remaining jacketedconductors 60 have their forward ends 70 also abutting the annularshoulder 46 within the terminal cup 30, but are not secured by theanchor bolts 74, nuts 82 and conductor clamps 68.

The non-anchored conductors are secured within the counterbore 44 by asoft solder filling 84 which is poured into the counterbore 42 in amolten condition after the two anchored conductors 64 have been boltedinto place. The assembly of the various parts of the conductor cable 10is believed to be clearly disclosed by the foregoing description of theconstruction thereof. The forward end portions 56 of the jacketedconductors 60 which are to be anchored, are originally of circular crosssection. Their forward end portions 56, however, are passed throughshort tubes of circular cross section (not shown) and these tubes andthe conductor end portions 66 within them are then swaged intorectangular cross section and become the tubular clamps 68 as shown inFIGS. 3 and 4. The swaging action tightly clamps the cable end portion66 firmly and nonremovably therein, after which the drilling of theclamping tube 68 and the conductor portion therein can be carriedOutJAnchoring is then performed in the manner described above, afterwhich the remaining cable ends 66 of the unanchored conductors 64 arethen inserted in the counterbore 44. This assembly is then placed in anupright position and molten soft solder is then poured into the cup 30so as to substantially fill the counterbore 44 and also the interior ofthe cable hose 38 substantially back to the forward end of theperforated conductor jackets 58.

In operation, the rearward cable terminal (not shown) of each cable 10is connected to the transformer while the forward blade 16 of theforward terminal 14 is bolted to its connection at the furnace. The port24 is connected to its corresponding pipe at the furnace while thecorresponding rearward terminal port is connected to a source of coolingwater. As a result, while the furnace is in operation, the heatgenerated by the flow of electric current thru each cable 10 and also bythe heat of the furnace itself is dissipated by the cooling waterflowing through the perforated fluted core 52 and thence around thejacketed conductors 60 by way of the perforations 54 and 62respectively.

If, for any reason, the flow of water through the cable 10 isinterrupted or shut off completely, the temperature rapidly rises withinthe cable 10 causing the solder filling 84 within the falling againstthe furnace casing or injuring adjacent workmen, either by their fallingweight or, more seriously and perhaps fatally, by the tremendouselectric current thus released, especially if water has fallen or isstanding upon the floor of the furnace room.

I claim:

1. A safety anchored electrical cable construction for electric arcfurnaces, said construction comprising a multiconductor electric cablehaving a hose with an array of flexible electrical conductors of thesame polarity encased therein and with a tubular liquid coolantconducting conduit extending through the center thereof,

an electric arc furnace connection terminal having a furnace connectionportion at its forward end and having a cable conductor connectionportion extending rearwardly from said furnace connection portion, saidcable conductor connection portion having a hollow cylindrical outerwall disposed within said hose in liquid-tight relationship therewithand defining a conductor receiving cavity therewithin,

the forward end portions of said conductors being disposed within saidcavity,

a heat-resistant mechanical conductor-clamping device disposed in saidcavity in engagement with the forward end portion of one of saidconductors and securing the same to the inner side of said outer wall inelectrical conducting relationship therewith,

and a fusible electrically conducting filler material also disposed insaid cavity and electrically connecting said cable conductor endportions to said cable conductor connection portion.

2. A safety anchored electrical cable construction, according to claim1, wherein an additional heat-resistant mechanical conductor-clampingdevice of similar construction and arrangement to said first-mentionedconductor clamping device is disposed in circumferentially spacedrelationship thereto and engages the forward end portion of a secondelectrical conductor and secures the same to said outer wall inelectrical conducting relationship therewith.

3. A safety anchored electrical cable construction, according to claim1, wherein said conductor-clamping device includes a conductor-anchoragemember secured to said outer wall and projecting inwardly therefrom intosaid cavity and wherein means is provided for securing said forward endportion of said one conductor to said conductor-anchorage member.

4. A safety anchored electrical cable construction, according to claim3, wherein said forward end portion of said one conductor has a holetherethrough, wherein said conductoranchorage member passes through saidhole, and wherein a locking element is secured to said member on theopposite side of said conductor end portion from said outer wall.

5. A safety anchored electrical cable construction, according to claim4, wherein said inwardly projecting member has a threaded portionthereon and wherein said locking element has a correspondingly threadedportion threadedly engaging said threaded portion of said inwardlyprojecting member.

6. A safety anchored electrical cable construction, according to claim1, wherein said filler material surrounds said conductor end portionsand said conductor-clamping device.

7. A safety anchored electrical cable construction, according to claim6, wherein said filler material substantially fills the space in saidcavity between said intermediate conduit and said outer wall and theinterstices of the individual wires of said conductor end portionsexclusive of the space therein occupied by the individual wires of saidconductor end portions and said clamping device.

1. A safety anchored electrical cable construction for electric arcfurnaces, said construction comprising a multiconductor electric cablehaving a hose with an array of flexible electrical conductors of thesame polarity encased therein and with a tubular liquid coolantconducting conduit extending through the center thereof, an electric arcfurnace connection terminal having a furnace connection portion at itsforward end and having a cable conductor connection portion extendingrearwardly from said furnace connection portion, said cable conductorconnection portion having a hollow cylindrical outer wall disposedwithin said hose in liquidtight relationship therewith and defining aconductor receiving cavity therewithin, the forward end portions of saidconductors being disposed within said cavity, a heat-resistantmechanical conductor-clamping device disposed in said cavity inengagement with the forward end portion of one of said conductors andsecuring the same to the inner side of said outer wall in electricalconducting relationship therewith, and a fusible electrically conductingfiller material also disposed in said cavity and electrically connectingsaid cable conductor end portions to said cable conductor connectionportion.
 2. A safety anchored electrical cable construction, accordingto claim 1, wherein an additional heat-resistant mechanicalconductor-clamping device of similar construction and arrangement tosaid first-mentioned conductor clamping device is disposed incircumferentially spaced relationship thereto and engages the forwardend portion of a second electrical conductor and secures the same tosaid outer wall in electrical conducting relationship therewith.
 3. Asafety anchored electrical cable construction, according to claIm 1,wherein said conductor-clamping device includes a conductor-anchoragemember secured to said outer wall and projecting inwardly therefrom intosaid cavity and wherein means is provided for securing said forward endportion of said one conductor to said conductor-anchorage member.
 4. Asafety anchored electrical cable construction, according to claim 3,wherein said forward end portion of said one conductor has a holetherethrough, wherein said conductor-anchorage member passes throughsaid hole, and wherein a locking element is secured to said member onthe opposite side of said conductor end portion from said outer wall. 5.A safety anchored electrical cable construction, according to claim 4,wherein said inwardly projecting member has a threaded portion thereonand wherein said locking element has a correspondingly threaded portionthreadedly engaging said threaded portion of said inwardly projectingmember.
 6. A safety anchored electrical cable construction, according toclaim 1, wherein said filler material surrounds said conductor endportions and said conductor-clamping device.
 7. A safety anchoredelectrical cable construction, according to claim 6, wherein said fillermaterial substantially fills the space in said cavity between saidintermediate conduit and said outer wall and the interstices of theindividual wires of said conductor end portions exclusive of the spacetherein occupied by the individual wires of said conductor end portionsand said clamping device.